Indian Journal of Pure and Applied Physics

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Volume 46

Number 9

SEPTEMBER 2008

CODEN: IJOPAU 46 (9) 603-674

                                                          ISSN: 0019-5596

 

 

 

 

CONTENTS

 

Atomic and Molecular Physics

 

Luminescence studies of MgSO4:Dy phosphors

607

R S Kher*, A K Upadhyay, S J Dhoble & M S K Khokhar

 

Vibrational spectra and modified valence force field for N,N˘-methylenebisacrylamide

611

B Venkatram Reddy* & G Ramana Rao

 

Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics and Fluid Dynamics

 

Interaction of 4 mm laser beam with absorption lines of sulphur dioxide

617

A Gohain Barua* & S Bhuyan

 

Physics of Gases, Plasmas and Electric Discharges

 

Small amplitude solitary waves propagating in a plasma with negative ions

621

Runmoni Gogoi, Nirupama Devi & G C Das*

 

Condensed Matter: Structural, Mechanical and Thermal Properties

 

Comparative study of two liquid models in the prediction of excess thermodynamic properties of liquid ternary systems 

629

R K Shukla*, Atul Kumar, Manoj Mishra & Preeti Dwivedi

 

Wave-vector and frequency dependent complex dielectric function and related physical properties of a weakly coupled one dimensional two component hot plasma

637

S P Tewari*, Jyoti Sood,Grima Dhingra & P Silotia

 

Growth of ZnSe single crystals by CVT technique and study micromorphology

646

M J Tafreshi* & M Fazli

 

Effect of adatom-phonon interaction on parameters of single walled carbon nanotube

651

S Patra

 

Thermal properties and electrochromic behaviour of PVA complexed electrolytes using PEG as plasticizer

657

P N Gupta

 

Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties

 

Dielectric spectroscopy of 100 MeV Ag ion irradiated polyetherimide*

660

Geetika Goyal & J K Quamara*

 

Interdisciplinary Physics and Ralated Areas of Science and Technology

 

Log-domain low pass high pass first-order filter

667

N A Shah*, S Z Iqbal & Nusrat Parveen

 

 

 

___________

*The corresponding author has been indicated by (*) mark in case of papers with more than one author.

 

 

 

 

                     

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 607-610

 

 

                              Luminescence studies of MgSO4:Dy phosphors

 

R S Kher*, A K Upadhyay**, S J Dhoble*** & M S K Khokhar****

*Departmentof Physics, Government Science P G College, Bilaspur 495 006

**Department of Physics, D P Vipra College, Bilaspur 495 001

***Department of Physics,Kamla Nehru College, Sakkardara, Nagpur 440 009

****Departmentof of Rural Technology, Guru Ghasidas University, Bilaspur 495 009

E-mail:kherrs@hotmail.com

Received 29 October 2007; revised 14 March 2008; accepted 19 June 2008

The lyoluminescence (LL) in MgSO4:Dy phosphors has been studied. Thermoluminescence (TL) and photoluminescence (PL) have also been studied to understand the mechanism of LL. MgSO4 phosphors containing different concentrations of Dy (0.05-1.0 mole%) have been prepared by solid-state diffusion method. The maximum LL intensity is observed for 0.05 mole% of Dy in MgSO4. TL glow curves of MgSO4:Dy phosphors are complex and peaks around 110, 150 and 220°C are observed. The effect of post-irradiation annealing on the LL shows that with removal of 220°C TL peak, the LL intensity decreases markedly. LL and TL intensity of MgSO4:Dy phosphors have also been recorded for different
g-doses. PL studies conducted on the sample show that Dy3+ ion acts as the luminescence center in MgSO4 phosphor.

Keywords: Lyoluminescence, Thermoluminescence, Photoluminescence, Magnesium sulphate

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 611-616

 

 

Vibrational spectra and modified valence force field for
N,N˘-methylenebisacrylamide

B Venkatram Reddy* & G Ramana Rao

University P G College, Kakatiya University,

Godavarikhani 505 209, Karimnagar Dist. Andhra Pradesh

Received 3 July 2007; revised 18 June 2008; accepted 3 July 2008

Raman and Fourier transform infrared (FTIR) spectra of N,N˘-methylenebisacrylamide have been recorded. A 35-parameter modified valance force field has been evaluated using 38-in-plane vibrational frequencies of the molecule. Unambiguous vibrational assignments have been made using eigenvectors and potential energy distributions computed in the process.

Keywords: Vibrational spectra, Valence force field, FTIR, Raman spectra

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 617-620

 

 

 

Interaction of 4 mm laser beam with absorption lines of sulphur dioxide

A Gohain Barua1,* & S Bhuyan2

1Department of Physics, Gauhati University, Guwahati 781 014

2Lakhimpur Girls’ College, North Lakhimpur 787 031

*E-mail: agohainbarua@yahoo.com

Received 21 September 2007; revised 2 June 2008; accepted 19 June 2008

Interaction of a free electron laser beam of wavelength 4 mm with rotational lines of sulphur dioxide has been studied. Values of transmittance, averaged over intervals of 0.1 cm-1, are obtained for absorber thickness 0.01, 0.1 and 1 atm-cm, using the quasi-random model of molecular band absorption. From these values, intensities of the high resolution absorption lines of SO2 are simulated in the frequency interval 2499.0115 – 2499.9910 cm-1.

Keywords: Sulphur dioxide lines, Quasi-random model, Free electron laser, Transmittance

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 621-628

 

 

 

Small amplitude solitary waves propagating in a plasma with negative ions

 

Runmoni Gogoi, Nirupama Devi & G C Das*

Department of Mathematics, Cotton College, Guwahati 781001, Assam

*Mathematical Sciences Division, Institute of Advanced Study in Science and Technology,
Paschim Boragaon, Guwahati 781 035, Assam

E-mail: runmoni_gogoi@rediffmail.com;  nirupama_cotton@rediffmail.com

Received 21 May 2007; accepted 15 May 2008

One-dimensional motion of positive ions, negative ions and electrons leading to the propagation of K-dV soliton has been considered. Different aspects of soliton amplitude and width have been studied in relation to density ratio (r), mass ratio (Q˘) of the plasma medium. The role played by the temperature of the negative ions is critically considered to find possible regions of soliton radiation. It is also observed that there are two mutually opposite directions of wave propagation due to the presence of negative ions.

Keywords: K-dV soliton, Soliton radiation, Sagdeev potential, Plasma, Small amplitude solitary waves

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 629-636

 

 

Comparative study of two liquid models in the prediction of excess  thermodynamic properties of liquid ternary systems

R K Shukla1, Atul Kumar1, Manoj Mishra2 &  Preeti Dwivedi3

1Department of Chemistry, 2Department of Physics, BND.College, Kanpur

3Department of Physics ,VSSD.College, Kanpur 208 002

Received 25 March 2008; revised 10 July 2008; accepted 14 July 2008

Excess thermodynamic properties i.e. excess volume, excess molar enthalpy, excess molar entropy, excess free energy and excess heat capacity have been evaluated using Prigogine-Flory-Patterson (PFP) and Bertrand-Acree-Bruchfield (BAB) theory for three ternary and its contributory binary liquid systems namely (1) tolune- cyclohexane- carbon tetrachloride and its contributory binaries (toluene+ cyclohexane), (cyclohexane  + carbon tetrachloride), (carbon tetrachloride + toluene); (2) benzene – cyclohexane- toluene and its contributory binaries, (benzene + cyclohexane), (cyclohexane + toluene), (toluene + benzene); (3) carbon tetrachloride- cyclohexane – benzene and its contributory binaries, (carbon tetrachloride + cyclohexane), (cyclohexane + benzene) and (benzene + carbon tetrachloride) at 298.15 K over a wide range of compositions. . The results so obtained from these two theories are very much comparable and are in good agreement.

Keywords:Excess thermodynamic properties, Ternary mixtures, Prigogine-Flory-Patterson theory, Bertrand-Acree-Bruchfield theory

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 637-645

 

 

Wave-vector and frequency dependent complex dielectric function and
related physical properties of a weakly coupled one dimensional
two component hot plasma

 

S P Tewari*, Jyoti Sood#,Grima Dhingra* & P Silotia*

*Department of Physics and Astrophysics, University of Delhi, Delhi 110 007

#Department of Physics, Panjab Univeristy, Chandigarh 160 014

E-mail:sptewari@physics.du.ac.in

Received 11 March 2008; revised 11 June 2008; accepted 20 June 2008

The complex dielectric function has been obtained for one dimensional two component weakly coupled classical and quantum hot plasmas in the entire wave-vector and frequency range. The related physical properties: dynamical structure factor and its singularities which yield collective modes, reflectivity of low energy photons and static pair correlation function about an impurity, positron, introduced in the plasma, have been computed and compared with the corresponding quantities in one component plasma. The results for the two plasmas are found to be markedly different.

Keywords: Semiconductors, Dielectric response, Plasma, Quantum hot plasma

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 646-650

 

 

Growth of ZnSe single crystals by CVT technique and study micromorphology

 

M J Tafreshia  & M Fazlib

aPhysics Department, bChemistry Department, Faculty of Science, Semnan University, Semnan, Iran

E-mail: m_jtafreshi@yahoo.com

Received 12 December 2007; revised 24 June 2008; accepted 1 July 2008

The vapour phase chemical transport in a closed tube has been investigated for a ZnSe-I2 system. Based on a proposed thermodynamic model, the optimum condition for the growth of ZnSe single crystals is determined. A good agreement has been observed between the predicted optimum growth parameters and the experimental results. ZnSe single crystals
are grown at different temperatures including optimum temperature for 2.5 mg/cm3 of iodine concentration. ZnSe single crystals grown at optimum temperature show better structural and morphological properties as compared to other temperature range.

Keywords:      Semiconductors, Crystal growth, Optical microscopy, Crystal Structure

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 651-656

 

 

Effect of adatom-phonon interaction on parameters of
single walled carbon nanotube

 

S Patra

Department of Physics, College of Basic Sciences and Humanities, G B Pant University of Agriculture & Technology
Pantnagar 263 145

Received 26 October 2007; revised13 March 2008; accepted 3 June 2008

Double time Green function technique and Zubarev equation of motion approach have been employed. The modified dependence with <nas> and chemisorption energy (DE) with radius of single walled carbon nanotube (SWCNT) was estimated. We considered HF approximation to decouple higher order Green function and found that the inclusion of adatom-phonon interaction, change the surface parameters. The comparison of theoretical predication and experimentally observed value indicates to study in detail from the first principle.

Keywords: Adatom-phonon, Nanotube, Carbon nanotube, Green function technique

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 657-659

 

 

 

Thermal properties and electrochromic behaviour of PVA complexed electrolytes using PEG as plasticizer

P N Gupta

Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221 005

E-mail: guptapn07@yahoo.co.in

Received 9 October 2006; revised 26 November 2007; accepted 14 July 2008

Thin films of PVA complexed with H3PO4 in different molar ratios using polyethylene glycol (PEG) as plasticizer are prepared by solution cast technique. Thermal study of the system of PVA-H3PO4-PEG indicates that glass temperature decreases as acid concentration increases in the presence of the plasticizer and hence, electrical conductivity of the complexed polymer increases. Thin films of higher conductivity are used in the fabrication of electrochromic devices. Optical absorption has been measured in transmission mode and time response of instantaneous change in optical density during colouring and bleaching sequence has been investigated by applying –5.00 to + 5.00V to the WO3 side with respect to ITO electrode for fixed duration. The modified device using PVA-H3PO4-PEG system shows maximum change in optical density (0.13 for the sample PVA- H3PO4) and gives higher value of contrast ratio due to high electrical conductivity. It is found that the plasticizer is effective to get shorter response time for the system of PVA- H3PO4 -PEG in comparison to the PVA- H3PO4 system for which observed colouration and bleaching times are 105 and 85 s, respectively.

Keywords: Complexed electrolytes, PVA, Plasticizer, Electrical conductivity, Electrochromic display

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 660-666

 

 

Dielectric spectroscopy of 100 MeV Ag ion irradiated polyetherimide

Geetika Goyal & J K Quamara*

Department of Physics, National Institute of Technology, Kurukshetra 136 119

Received 24 April 2008; accepted 8 July 2008

The dielectric constant (e′) and loss factor (e′′) have been measured in pristine and 100 MeV Ag ion irradiated (fluences: 5.6´1010, 1.8´1011 and 1.8´1012 ions/cm2) polyetherimide (PEI) in the temperature region 30-250°C at different frequencies ranging from 200 Hz to 5 MHz. There is an overall increase in e′ in irradiated samples. This shows the dominance of interfacial polarization arising from the large number of radiation induced defect sites and free radicals. However, the increase in e′ is not directly proportional to the fluence of irradiance. There is a sudden decline in e′ at intermediate fluence (1.8´1011ions/cm2) which is due to the occurrence of new secondary radiation induced crystalline (SRIC) phase. In the low temperature region 30-100°C, the e′ follows the Kirkwood model. Above 100°C, the e′ is almost temperature independent. The radiation induced free radical cross-linking and formation of free radicals have been held responsible for this behaviour. Various relaxation processes revealed their presence in the form of loss peaks in e′′-T curves appearing around 40-50°C, 120-130°C and 180-220°C associated to the dipolar nature of ether linkages, carbonyl groups and space charge relaxation processes, respectively.

Keywords: High energy heavy ion irradiation, Polyetherimide, Dielectric spectroscopy

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, September  2008, pp. 667-670

 

 

 

Log-domain low pass high pass first-order filter

N A Shah 1, S Z Iqbal 2 & Nusrat Parveen1

Department of Electronics and Instrumentation Technology, University of Kashmir, Srinagar 190 006

E-mail: nassgr@yahoo.co.uk; nusrat.parv@gmail.com; zaffer121@rediffmail.com

Received 11 July 2007; revised 7 June 2008; accepted 1 July 2008

A new first-order log-domain filter topology implementing simultaneously low-pass (LP) and high-pass (HP) filter functions has been presented. The circuit employs log-domain cells, current sources and grounded capacitor. The circuit has simple architecture, wider dynamic range at low power supply and higher frequency operation as it is based on log-exponential relation of a transistor. The electronic tunability of the proposed filter and grounded capacitor make it suitable for construction in IC technology. The PSPICE simulations results are found to be in close conformity with the
theoretical results.

Keywords: Log-domain filter, First-order filter, High frequency applicability